Influence of silica nanoparticle incorporation on the wettability, oil affinity, and dye removal properties of blow-spun polymeric membranes

The versatility and scalability of blow spinning motivated us to investigate the surface properties of blow-spun poly(ε-caprolactone) (PCL), cellulose acetate (CA), polystyrene (PS), and their blends, with and without silica nanoparticles (SiO2 NPs). Pristine PCL and PS membranes are hydrophobic and oleophilic, whereas CA membranes are hydrophilic and oleophilic. Incorporation of SiO2 NPs renders PCL membranes superhydrophilicity while preserving oleophilicity. Blending PS with CA or PCL yields hydrophobic and oleophilic membranes. These characteristics enable selective oil uptake and either water repellence or water spreading, depending on formulation. Dye removal was assessed using methylene blue (MB), showing rapid uptake on PS/CA and higher overall removal for PCL–SiO2 NPs membranes. SiO2 NPs incorporation was confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Under the conditions tested (1 mL MB solution), a PCL-SiO2 NPs membrane (6.9 cm2, 118 μm thick, 24.6 mg) reduced the MB concentration by ~ 4 mg L−1 within 19 h (~ 4 μg removed; apparent uptake ~ 0.16 mg g−1). Overall, blow spinning provides an accessible route to obtain membranes for oil–water separation and dye retention.